As is well known, the cathode parts of aluminum reduction cell which contact with molten aluminum and electrolyte bath are composed of carbon material. Cathode blocks tend to deteriorate due to cracks caused by thermal stress and/or swelling due to sodium penetration during the operation. In addition to this, cathode blocks tend to be abraded and worn due to the movement of sludge, which contains suspended alumina, over the cathode blocks. This movement is caused by the flow of molten alumina by magnetic field. Due to these reasons, cathode blocks can have a short life span and reduction cells can fail.
In order to prolong the life span of cathode blocks, graphitized cathode blocks which are graphitized at over 2000° C. were disclosed and are currently being used (see Patent Document 1: Japanese Patent Laid-open No. sho 52-119615). Graphitized cathode blocks showed an excellent resistance against thermal stress and sodium penetration, and consequently pot failures due to these reasons have been prevented.
[Problem(s) to be Solved]
However, graphite is basically very soft material, therefore, the problem against abrasion is not completely solved. This means life of a pot with graphitized cathode blocks is rather short due to cathode blocks' deterioration caused by abrasion, and it is necessary to improve the abrasion resistance of cathode blocks to attain longer pot life span.
[Object(s) of the Invention]
This invention has been made by considering the fact described above, and the object thereof is to supply cathode blocks with higher abrasion resistance to attain longer pot life span and its manufacturing process.